"Is there water still on Mars? I don't have a view on that because we don't have good data to answer that question. One of the biggest mistakes you can make if you're a scientist is to think you know the answer, or wish for a certain answer, before you actually have it."

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Learn to think and judge for yourself, responsibly. Don't accept everything without criticism and as absolutely true, everything which is brought to your attention. Learn from life. The biggest mistake of my life was that I believed everything faithfully which came from the top, and I didn't dare to have the least bit of doubt about the truth of that which was presented to me. Walk through life with your eyes open. Don't become one-sided; examine the pros and cons in all matters.

— Rudolf Hoss